import { describe, expect, it } from 'vitest';
import { ceilDiv, formatUnits, parseDecimalToUnits, toleranceFloor } from '../src/amounts';

describe('parseDecimalToUnits', () => {
  it('parses whole and fractional amounts', () => {
    expect(parseDecimalToUnits('100', 6)).toBe(100_000000n);
    expect(parseDecimalToUnits('100.25', 6)).toBe(100_250000n);
    expect(parseDecimalToUnits('0.000001', 6)).toBe(1n);
  });

  it('rejects garbage, negatives, exponents, and excess precision', () => {
    for (const bad of ['', 'abc', '-5', '1e3', '1.', '.5', '1.2345678']) {
      expect(() => parseDecimalToUnits(bad, 6)).toThrow();
    }
  });
});

describe('formatUnits', () => {
  it('round-trips and trims trailing zeros', () => {
    expect(formatUnits(100_250000n, 6)).toBe('100.25');
    expect(formatUnits(1n, 6)).toBe('0.000001');
    expect(formatUnits(100_000000n, 6)).toBe('100');
  });
});

describe('toleranceFloor', () => {
  it('computes the 1% floor exactly', () => {
    expect(toleranceFloor(100_000000n, 100)).toBe(99_000000n);
  });

  it('rounds fractional floors UP so nothing below true tolerance ever qualifies', () => {
    // 33.333333 × 0.99 = 32.99999967 → floor must be 33.000000
    expect(toleranceFloor(33_333333n, 100)).toBe(33_000000n);
  });

  it('zero tolerance floor equals the required amount', () => {
    expect(toleranceFloor(100_000000n, 0)).toBe(100_000000n);
  });

  it('rejects out-of-range tolerance', () => {
    expect(() => toleranceFloor(1n, -1)).toThrow();
    expect(() => toleranceFloor(1n, 10001)).toThrow();
  });
});

describe('ceilDiv', () => {
  it('rounds up only when there is a remainder', () => {
    expect(ceilDiv(10n, 5n)).toBe(2n);
    expect(ceilDiv(11n, 5n)).toBe(3n);
    expect(ceilDiv(0n, 5n)).toBe(0n);
  });
});